IT22 - Mar Piccolo of Taranto - Italy
IT22 - Mar Piccolo of Taranto
Heavy metal deposition
The Mar Piccolo is an inner, semi-enclosed sea located on the North of the town of Taranto showing lagoon features. It has a surface area of 20.72 Km2 and is divided by two promontories of land into two smaller inlets, called the First and the Second Inlet, which have a maximum depth of 12 and 8 m, respectively. Two canals, Navigable Canal (width 58 m, depth 12 m) and Porta Napoli Channel (width 48 m, depth 2.5 m), the most important for the water exchange, put the Mar Piccolo in communication with the nearby Mar Grande basin. The scarce hydrodinamism and the reduced water exchange, mainly in the Second Inlet, with the nearby Mar Grande determine the stratification of the water, especially in summer. Due to the strong anthropogenic impact, most of hard substrata are artificial. Soft substrata are sandy near the shore and muddy in the central zone of both Inlets. In the Mar Piccolo basin, tidal range is reduced, not exceeding 30-40 cm. Chemical-physical features of the basin, deeply studied in the last years, show a variable trend according to the seasons and to the Inlets. The two basins are characterized by different levels of confinement. Such a confinement is evident for chemichal-physical variables and let to immediately single out the two basins, as the variables values change moving from the First Inlet to the Second Inlet. Always along the same direction, besides the confinement, an evident increase of all the variables fluctuations is observable which points out a noticeable instability of the most confined basin. The lagoon features of the Mar Piccolo are mainly due to the presence of 34 submarine freshwater springs (locally called "Citri") of which 20 are in the First Inlet and 14 in the Second Inlet . The most important are “Galeso” (mean flow 600 L s-1) and “Citrello” (mean flow 350 L s-1) in the First Inlet and “Le Copre” (mean flow 80 L s-1) in the Second Inlet. The freshwater of the “Citri” has a uniform temperature of 18°C; therefore, they locally affect both the salinity and the temperature of seawater. Moreover, in the Mar Piccolo several small tributary rivers flow, of which the most important is “Galeso” (mean flow 50,000 m3day-1) in the First Inlet; other small rivers, less important because their flow is strongly affected by the seasons, are “Cervaro”, “Rasca” and “Rubafemmine” in the Second Inlet. Salinity ranges from 34.3 to 37.7. Seawater temperature ranges from 7.1°C to 33.6°C. Since the Mar Piccolo is an enclosed and therefore sheltered basin, it has been using for human activities for a long time. Indeed, it houses the biggest mussel farm in Italy with plants widely distributed in both the Inlets, which has a production of about 30,000 tons year-1 and employs about 800 people. Until few years ago, the most important Italian Navy base was located in the First Inlet of which only the dry-docks are still present. In addition, a small fishing fleet, of about 300 boats, is present in the First Inlet. The water-scooping machine of the steel industry catches seawater from the basin for the cooling plants. Moreover, the Mar Piccolo is subject to agricultural pollution because the irrigating waters of the surrounding fields flow into the basin by both the rivers and the submarine freshwater springs. Up to 2000, also 14 urban sewage outfalls flowed into the basin coming from some small cities near Taranto. Starting from this year, the outfalls of 11 of these were closed since their seawage pipes were connected to Bellavista depuration plant flowing outside the Mar Grande basin; currently, only 5 seawage outfalls (1 in the First Inlet and 4 in the Second Inlet) till flow into the basin. Therefore, the discharging of waste waters in the basin has noticeably been reduced.
General Characteristics, Purpose, History
The current scientific activities performed on the Mar Piccolo concern the continuation of studies on biodiversity of phytobenthos (seaweeds and phaerogams), zoobenthos, phytoplankton, microbial communities, as well as the chemical-physical features of the basin, and the impact of metals, IPAs and PCBs in marine sediments and edible mollusks. New investigation issues are: alien species, bioactive compounds from marine biomasses, new species in aquaculture, zooplankton, cyanopicoplankton. The Project "Life4MarPiccolo" (LIFE14 ENV/IT/000461) is ongoing, which provided the set up of a pilot plant for sediment treatment based on innovative microfiltration technology. On may 2018, within Horizon 2020 "Cyano Alert" (H2020-EO-2016-Earth Observation-730141), remote sensing calibration with in situ phytoplankton sampling started aiming to bloom forecasting.
The Mar Piccolo basin was been studying since the first years of the last century when the Institute for Marine Coastal Environment of Taranto was built and named Royal Institute for Marine Biology. In that period the basin was studied from different points of view in order to set up the best conditions for mussel culture. To this purpose, chemical-physical studies on temperature, salinity, dissolved oxygen of seawater were the first to be carried out. As the years went by, other chemical-physical variables were investigated (e.g. nutrients, chlorophyll) and, starting from 1990’s, also suspended matter was considered. Extensive studies on biodiversity were also performed. The first investigations on the biota were those on macroalgae which date back to the beginning of the last century. They were floristic studies and the papers do not report long lists of species but only some observations on a few taxa; however, all the samples collected in the Mar Piccolo are kept in exsiccata in a rich herbarium (Pierpaoli Herbarium), which can be considered in the same way as a historical series of data. Successively (from 1969; 1970; 1983; 1984), some sporadic information on macroalgae was also included in generic papers about the basin. Only at the end of the eighties, the accurate study of the phytobenthos was undertaken, from both a floristic and a vegetational point of view which is still ongoing. Also studies on zoobenthos date back to the half of the last century and are still ongoing. Nowadays, the basin is constantly monitored to follow the trend of the most important chemical-physical variables, to observe changes in the composition of the biocenoses and to early detect the presence of alien species. Studies on the diversity of bacteria began in the 1980’s whereas investigations on phytoplankton (active stages and resting stages) and nekton, especially juveniles of commercially important species, are more recent but important series of data are already available. Moreover, starting from 1990’s the basin has been extensively studied also concerning the impact of metals (Hg, Pb, Cd, Cu, Zn, Ni and V), IPAs and PCBs in marine sediments and edible mollusks.
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